Alderney Sea Temperature
Looking to find out what the sea water temperature in Alderney is for today and the next few days? Below are data and charts that will give you information about sea temperatures in Alderney and nearby locations.
Water temperature in Alderney right now
Below is the current sea temperature for Alderney, Channel Islands on 6th December 2025.
13.8° C
(56.84° F)
- yesterday: 13.82° C (56.88° F)
- a week ago: 13.43° C (56.17° F)
Water at this temperature is cold and will feel very cold initially, but the body will get used to it and longer swims are possible. Experienced swimmers can manage several hours of swimming, however hypothermia is still a very big risk.
The average sea temperature for Alderney on December 6th over the last 10 years is 13.09° C (55.56° F), with a low temperature of 12.22° C (54° F) and a high of 13.84° C (56.91° F).
Analysis and forecast for Alderney water temperatures
The water temperature in Alderney today is higher than the average temperature of 13.09° C (55.56° F) and the temperature on this day last year, 6th December 2024, was 13.84° C (56.91° F).
The chart and table below shows the change in water temperature in Alderney over the last 30 days:
The actual nearshore temperatures may vary by several degrees and this can also be heavily affected by weather. Strong winds can cause cold, deep waters to replace the surface waters that had been warmed by the sun, and heavy rain can also reduce the temperature of the sea surface temperature as well.
Water temperature in Alderney by month
The chart below shows the monthly average water temperature in Alderney.
For more detailed information on how the sea temperature in Alderney changes for each month of the year, choose from the months below.
Alderney map and nearby water temperatures
Locations near Alderney
The highest temperature in Channel Islands today is 13.91° C (57.04° F) in Alderney. The lowest is in Jersey, where the temperature of the water is 13.21° C (55.78° F).
Why measure sea surface temperatures (SST) in Alderney?
The ocean covers about 71% of the Earth's surface, and scientists record the sea surface temperature (SST) of locations such as Alderney because they want to understand and learn how the ocean communicates with the atomosphere of Earth.
SST is one measure that provides information on the global climate, and it can be used to predict the weather in Alderney as well as atmospheric model simulations and to study marine ecosystems in the area.
Data source and citation
Raw data for the calculations made to find the sea surface temperature in Alderney comes from the National Oceanic and Atmospheric Administration (NOAA) and their 1/4° daily Optimum Interpolation Sea Surface Temperature.
The water temperature data is constructed by combining observations from different platforms (satellites, ships, buoys, and Argo floats) on a regular global grid. A spatially complete sea surface temperature map is then built by interpolating to fill in gaps in the data.
If you'd like to use any of the information above in the format it is presented, please use the citation tool below.
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<a href="http://seatemperatures.net/europe/channel-islands/alderney/">Alderney Sea Temperature</a>
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"Alderney Sea Temperature". SeaTemperatures.net. Accessed on December 6, 2025. http://seatemperatures.net/europe/channel-islands/alderney/.
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"Alderney Sea Temperature". SeaTemperatures.net, http://seatemperatures.net/europe/channel-islands/alderney/. Accessed 6 December, 2025
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Alderney Sea Temperature. SeaTemperatures.net. Retrieved from http://seatemperatures.net/europe/channel-islands/alderney/.